thumb|Common Swift chicks

The common swift (Apus apus) is a medium-sized bird, superficially similar to the barn swallow or house martin but somewhat larger, though not stemming from those passerine species, being in the order Apodiformes. The resemblances between the groups are due to convergent evolution, reflecting similar contextual development. The swifts' nearest relatives are the New World hummingbirds and the Southeast Asian treeswifts.

Its scientific name Apus is Latin for a swift, thought by the ancients to be a type of swallow with no feet (from Ancient Greek α, a, "without", and πούς, pous, "foot"). The current genus Apus was erected by the Italian naturalist Giovanni Antonio Scopoli in 1777 based on tautonymy. The word apus is the Latin word for a swift. It is derived from the Ancient Greek α, a, "without", and πούς, pous, "foot", based on the belief that these birds were a form of swallow that lacked feet.

Behaviour

thumb|Eggs of Apus apus

thumb|right|Young bird, not yet able to fly

thumb|Several swifts flying

thumb|Swifts in flight, [[Tomaszów Mazowiecki, Poland]]

Swifts may nest in former woodpecker tree burrows found in ancient forests, such as some 600 reported nesting in the Białowieża Forest of North Eastern Poland, or the small colony found in a combination of woodpecker holes and tree nestboxes on the RSPB's reserve at the Caledonian Forest in Abernethy, Scotland. While tree holes and cliffs may have comprised their historical nesting resource, the almost complete removal of ancient forest from their nesting range has resulted in adaptation to man-made sites. Swifts build their nests of air-borne material caught in flight, bonded with their saliva, in suitable buildings hollows, such as under tiles, in gaps beneath window sills, and most typically under eaves and within gables.

Swifts form pairs that may couple for years, and often return to the same nesting site and partner year after year, repairing degradation suffered in their 40-week migratory absence. Insects such as clothes moths, carpet and larder beetles may consume all but the most indigestible nest elements, typically feather shafts.

Young nesting swifts are able to survive for a few days without food by dropping their body temperature and metabolic rate, entering a torpid state.

Except when nesting, swifts spend their lives in the air, living on the insects caught in flight; they drink, feed, and often mate and sleep on the wing. No other bird spends as much of its life in flight. Contrary to common belief, swifts can take flight from level ground. Their maximum horizontal flying speed is Over a lifetime they can cover millions of kilometers.

Feeding parties can be very large in insect-rich areas, such as wetlands. Reports of as many as 2,000 swifts feeding over flooded gravel pits, lakes and marshy river deltas are not uncommon, and may represent an ingress of swifts from within as much as a radius; swifts nesting in Western Scotland are thought to venture to Lough Neagh in Northern Ireland to feed on the abundant and nutritious "Lough Neagh Fly".

Breeding

Common swifts nest in a wider variety of sites than any other species of Apus. Swifts usually nest in buildings but they can also be found nesting in holes in trees, cliffs and crevices, and even in nestboxes. Swifts usually enter their nesting holes with direct flight, and take-off is characterized by an initial free-fall. Common swifts have also been recorded in the Caribbean, including in Bonaire, Barbados, and Puerto Rico. In South America, there are records in Suriname, French Guiana, Brazil, and Colombia.

Migration

Subjects of a geolocator tracking study demonstrated that swifts breeding in Sweden winter in the Congo region of Africa.

The heraldic bird known as the "martlet", which is represented without feet, may have been based on the swift, but is generally assumed to refer to the house martin; it was used for the arms of younger sons, perhaps because it symbolized their landless wandering.

See also

  • International Swift Conference
  • Unihemispheric slow-wave sleep

References

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  • Swift Conservation Homepage Swift Conservation.Org free advice on the natural history and conservation of Apus apus the Common Swift
  • Ageing and sexing (PDF; 3.1 MB) by Javier Blasco-Zumeta & Gerd-Michael Heinze
  • The Common Swift
  • Feathers of Common Swift (Apus apus)
  • Common swift species text in The Atlas of Southern African Birds
  • Nesting swifts webcam in the tower of the Oxford University Museum of Natural History, UK